As was to be expected, ‘arcgis’ (549 times) is the most used tag followed by ‘arcgis-10.0′ ;)

From an open source perspective, PostGIS gets most attention (rank 8), followed closely by OpenLayers (rank 9) and Geoserver (rank 10). QGIS is the highest-ranked desktop GIS (rank 13). Users of other open source desktop GIS like uDig or gvSIG don’t seem to be using this platform yet.

Here’s the full list of open source GIS tags with a count of more than 10: